Automotive strip serpentine fin



Oct. 10, 1961 V J. D. MORSE 3,003,749

AUTOMOTIVE STRIP SERPENTINE FIN Filed Sept. 9, 1957 u may i ill'lilil i li TlWlilil i llil lilil J6 J7 J5 22266 Z7. -%r6e.

dvwd A United States Patent Q 3,003,749 AUTOMOTIVE STRIP SEREENTINE FIN James D. Morse, Racine, Wis., assignor to Modine Manufacturing Company, Racine, Wis., a corporation of Wisconsm Filed Sept. 9, 1957, Ser. No. 682,910 6 Claims. (Cl. 257-130) This invention relates generally to heat exchange structures, and more particularly to a novel fin structure and arrangement.

The invention has among its objects the production of a heat exchange fin structure which may incorporate the advantages of the invention illustrated in US. Letters Patent 2,789,797, issued Aug. 23, 1957, to C. S. Simpelaar, and in addition thereto provide a high degree of turbulence and mixing of the fluid flow through the fin structure to achieve very high heat exchange efficiency.

Another object of the invention is the production of a heat exchange fin structure having the above advantages, which is so designed that the flow through the fin structure may alternately change the air flow direction and form an undulating path through the structure, and in which the fluid entering the structure may leave at substantially a corresponding point at the rear of the structure so that the change in flow direction will not introduce undesirable laterally acting forces on the exchange structure.

A further object of the invention is the production of such a fin structure which is particularly adaptable for use on so-called serpentine type fin arrangements, as well as other types of fin structures.

Many other objects and advantages of the invention will be obvious to those skilled in the art from the disclosure herein given.

In the drawings, wherein like reference characters indicate like or corresponding parts:

FIG. 1 is a perspective View of a portion of a heat exchange structure embodying serpentine fins to which the invention may be readily applied;

FIG. 2 is a front elevational view of a serpentine fin structure constructed in accordance with the present invention;

FIG. 3 is a semi-diagrammatic transverse section in the direction of fluid flow through the fin structure and corresponding generally to a section taken approximately on the line 3-3 of FIG. 6;

FIG. 4 is a sectional figure similar to FIG. 3, illustrating a modified arrangement of fin elements;

FIG. 5 is a sectional view similar to FlGS. 3 and 4 of still another modified arrangement; and

FIG. 6 is a front elevational view similar to FIG. 2 of a fin structure embodying the invention, and constructed from a series of nested channel shaped members.

The present invention is directed to a fin structure which is of particular application in heat exchangers such as automotive radiator cores wherein heat transfer is effected between a liquid coolant flowing through a series of conduits or passageways and air flowing between such passageways, suitable fin structures being interposed in the air passageways to increase the heat transfer between the two mediums. The superior characteristics of so-called strip fins have been known for some time,

3,003,749 Patented Oct. 10, 1961 iQQ and the previously referred to Simpelaar patent discloses the advantages to be gained by suitably spacing in-line strip fins to prevent a laminar carry-over from a preceding fin to a succeeding fin, with a resultant gain in heat exchange efificiency. However, while this patent disclosed strip fins which were arranged at a slight angle with respect to the direction of flow through the fin structure, the fluid flow through the fin structure was substantially in a single direction more or less normal to the plane of the series of fins forming the leading face of the exchange structure.

The present invention contemplates the use of strip fins arranged at a substantially pronounced angle with respect to the direction of flow of fluid entering the structure, in combination with fin members which are of such size and shape that fluid flow from the strip fins will impinge on a face of the fin element and change the direction of the flow of fluid leaving the fin element with respect to the fluid striking the element. The arrangement preferably is repeated whereby an undulating or serpentine flow pattern through the pass or fin structure is achieved, and in which the various flow segments are being successively broken up and divided into different paths. The resulting turbulence, dividing and intermixing of air paths through the structure, results in improved efiiciency of a heat exchanger embodying the invention and thus enables either a reduction in size and weight of the exchanger for a given capacity, or an increase in capacity for an equivalent sized exchanger.

Referring to the drawings and particularly to FIGS. 1, 2 and 3, FIG. 1 illustrates a section of the heat exchange structure comprising a plurality of generally vertically extending fluid conducting tubes 1 which are laterally spaced by fin structures 2 formed from relatively thin sheet or strip material which is reversely folded back and forth upon itself to form a serpentine structure having a series of corrugations 3.

Referring to FIGS. 2 and 3, the serpentine fin structure 2 is provided with a plurality of transversely extending fin strip elements 4, with successive strip elements being connected adjacent corresponding edges, forming the corrugations 3. Each of the elements 4 may be suitably formed to provide a plurality of strip fins 6. As will be apparent from a reference to FIG. 3, the strip fins 6 are arranged in substantially aligned series which extend in planes substantially normal to the direction of fluid flow entering the fin structure, the series being arranged in groups which in turn are disposed in a sequential repeating pattern. In the particular embodiment illustrated in FIG. 3, three groups of strip fins 6 are illustrated each comprising three series of five fins, the second group having the fins thereof disposed at a reverse angle with respect to the direction of flow of the entering fiuid, while the third group is arranged in the same manner as the first. Formed in each strip element 4 intermediate the groups of fins 6 formed therein are deflecting fin members 7 which are provided with substantially parallel intermediate portions 8 extending in substantially the same direction as the fluid flow entering the structure, and leading and trailing angularly directed portions 9 and 11 which extend in the same direction as the fins of the adjacent group with which they are as sociated. V

As illustrated in FIG. 3, the fins 6 and the portions 9 and 11, respectively, of the intermediate members '7 may be so arranged that all of the fins 6 of any one group are out of line in the direction of air flow therealong, or in other words lie in planes oflset from each other, although obviously it would be possible so to proportion the angle and dimensions of the fins that a succeeding fin in one series might be in line with a preceding fin in a non-adjacent series. In other words, no fin or fin portion in one series has aligned therewith a fin or fin portion in the immediately following series. In like manner in connection with the serpentine structure such as illustrated in FIG. 2, the flow pattern will vary with tthe spacing of the corrugations and also vary transversely across the face of the fin strip element 4 due to the angular relation between adjacent elements 4 depending on variations in the fin spacing. Consequently, in most cases it is desirable to so proportion and arrange the fines that the advantages of the invention disclosed in the previously referred to patent may be utilized. As illustrated, preceding the first group of strip fins 6 is a series of fin elements 12, haw'ng trailing portions 11 so that the elements 12' in eifect each correspond to the trailing half of the members 7, and in like manner, following the last group of fins 6 is a series of trailing elements 12 having leading angularly disposed portions 9 so that the elements 12 generally correspond to the leading half of the members 7. Thus one full pattern extends from the leading face, comprising the leading edges of the fin elements 12', to the middle of the intermediate portions 8' of the fin members 7 the particular fin structure illustrated in FIG. 3 comprising one full pattern and a subsequent half pattern. Obviously, if desired the number of repetitious patterns may be varied as may be required or desired.

It will be apparent that in operation, due to the offset arrangement of the fins, air entering the fin structure between adjacent fin elements 12' will be initially divided into two paths by the adjacent strip fin 6 of the first series, which may be designated as upper and lower paths. The upper path will in turn be intermixed with the lower path of air divided by the strip fin immediately above it, and in like manner the lower path will be intermixed with the upper path of air divided by the strip fin 6 immediately below it. Such intermixed air in each path will in turn be divided by the strip fins of the second series and each division intermixed with air similarly divided by the fine above and below, a similar action taking place with tthe fins of the third series of the first group. The portions 9 of each fin member 7 will similarly divide the incoming air, the intermediate portion 8 deflecting the air and reversing the flow which was generally upward through the first group of fins to a generally downward flow through the second group of fins 6'. The intermixing and dividing action described with the first group will be repeated in the second group of fins 6, with the exception that the general direction of the air is downward instead of upward. As the air strikes the tin members 7, the direction of flow will again be reversed upwardly through the second gnoup of fins 6, and the air will leave the structure between the elements 12 with substantially the same direction of flow as it entered the structure, and will be discharging from the rear face at substantially the same level at which it entered the front face. I have found that excellent results may be achieved utilizing an angle of from twenty-two to thirty degrees on the fin elements, the angle being measured with respect to the plane of the fin strip element 4, although, depending upon structural and functional requirements, it may be desirable to reduce or increase the fin angle in particular applications as may be readily determined at the time by suitable tests.

The construction illustrated in FIG. 4, while utilizing the same general concept as the construction illustrated in FIG. 3, utilizes a pattern which in the particular fin illustrated repeats itself three times as compared with one and one-half times in the construction shown in FIG. 3, and utilizes two different types of deflecting fin elements. Thus the structure utilizes a leading series of fin elements 12 having angularly extending portions 11', followed by a series of fin elements 14, each of which comprises angular extending portions 15 and 16, followed by a series of strip fins 6 which extend in parallel relation. The proportions of the fins and angular portions preferably are such that adequate spacing is provided between any in-line fins to take advantage of the invention illustrated in the patent heretofore referred to.

In FIG. 5 there is shown a construction substantially similar to that of FIG. 3 and employing the same concept, but with the fins difierently proportioned. In the structure as shown, three groups of fins 17 and 17' are provided, each comprising six series of three fins each, there being three strip elements corresponding to the elements 4 in the structure. Each of these groups of fins 17 and 17 is of substantially the same extent in the direction of fluid flow as the corresponding three groups of fins 6 and 6' of the FIG. 3 structure, but since six fins 17 or 17 are provided in the same distance as three fins 6 or *6, the fins 17 and 17 are considerably narrower, that is, smaller in the dimension along the direction of fluid flow, than the fins 6 and 6'. Extending between the fin groups are intermediate members 7 and 7' shown and described in connection with the construction of FIG. 3, and having angularly disposed portions 18, 19, and 18', 19', respectively corresponding to the portions 9, 11, and 9', 11' previously described. The structure of FIG. 5 is generally similar to that of FIG. 3 in the offset fin arrangement and the breaking up and mixing of air or other fluid flowing through the structure, and in the reversal of the direction of flow by the intermediate fin members. The breaking up and intermixing of the various fluid streams difiers from the particular action in the FIG. 3 structure, due to the difference in number and proportions of the fins 17 and 17 The heat exchanger or similar finned structure shown in FIG. 6 comprises a series of generally channel-shaped finned members each having a fin strip element 4' similar to the strip element '4 of the fin structure 2 with parallel flanges 21 extending along opposite edges thereof. Each flange has at its free edge a marginal portion 22 which is offset outwardly a distance substantially equal to the thickness of the material. The channel-shaped constructions may thus be assembled in nested relation as shown in the figure, with the flanges 21 of one received between the offset flange portions 22 of another. Any desired number of fluid passages may thus be provided, with any desired arrangement and pattern of fins formed in the strip elements 4, as previously described.

It will be noted from the above description that I have provided a novel fin structure wherein fins are positioned angularly with respect to the original direction of fluid flow, such fins being so shaped and arranged as to provide an undulating or serpentine flow through such fluid passes of the exchange structure as distinguished from previous structures which might also use angularly disposed fins, but so arranged that the flow is substantially straight through the structure or which while extending at an angle runs straight through the core from one face to the other in a. single direction, or spirals through the core.

Tests on core structures embodying the present invention have disclosed that a very useable gain in efiiciency is achieved whereby the weight may be reduced by use of the present invention in a core having a capacity equivalent to prior heavier and larger structure. It will be particularly noted that the present invention provides a high degree of intermixing and turbulance without unduly or undesirably increasing flow resistance through the core, resulting in a compact, light weight structure of very high efiiciency.

Having thus described my invention, it is obvious that various immaterial modifications may be made in the same without departing from the spirit of my invention; hence I do not wish to be understood as limiting myself to theexact form, construction, arrangement and combination of parts herein shown and described, or uses mentioned.

I claim:

1. In a fluid pass for a heat exchanger, the combination of, an elongated fluid pass structure, a plurality of relatively narrow and substantially planar fins having their ends operatively connected to the opposite sides of the elongated fluid pass structure in heat transfer relation therewith, the respective relatively narrow and substantially planar fins extending transversely of the axis of fluid flow through the elongated fluid pass structure, said relatively narrow and substantially planar fins being ar ranged in a plurality !of spaced groups, each of said spaced groups extending across the elongated fluid pass structure transversely to said axis of flow therethrough, said relatively narrow and substantially planar fins being spaced from each other for each of said spaced groups, each of said relatively narrow and substantially planar fins extending at an angle with respect to the direction of flow, all of the relatively narrow and substantially planar fins of each spaced group extending in the same general direction, the angle of the relatively narrow and substantially planar fins of each spaced group being reversed with respect to the angle of the relatively narrow and substantially planar fins of the next adjacent spaced group, and a deflecting fin member positioned between said spaced groups of reversely directed and relatively narrow and substantially planar fins, each deflecting fin member including portions respectively extending in the same angular direction as the relatively narrow and substantially planar fins of the spaced groups to provide undulating fluid flow paths through said elongated fluid pass structure.

2. In a fluid pass for a heat exchanger, the combination of, an elongated fluid pass structure, a plurality of relatively narrow and substantially planar fins having their ends operatively connected to the opposite sides of the elongated fluid pass structure in heat transfer relation therewith, the respective relatively narrow and substantially planar fins extending transversely of the axis of fluid flow through the elongated fluid pass structure, said relatively narrow and substantially planar fins being arranged in a plurality of spaced groups, each of said spaced groups extending across the elongated fluid pass structure transversely to said axis of flow therethrough, said relatively narrow and substantially planar fins being spaced from each other for each of said spaced groups, each of said relatively narrow and substantially planar fins extending at an angle with respect to the direction of flow, all of the relatively narrow and substantially planar fins of each spaced group extending in the same angular direction, the angle of the relatively narrow and substantially planar fins of each spaced group being reversed with respect to the angle of the relatively narrow and substantially planar fins of the next adjacent spaced group, a deflecting fin member comprising an intermediate portion and leading and trailing angularly directed portions extending in the same direction as the relatively narrow and substantially planar fins of the aforesaid spaced groups with which the leading and trailing angularly directed portions are associated to provide undulating fluid flow paths through said elongated fluid pass structure, and the intermediate portion of said deflecting fin member extending substantially parallel to said axis of fluid flow through said elongated fluid pass structure.

3. A heat exchange structure comprising a plurality of laterally spaced, elongated fluid conducting tubes, fin structures positioned between said laterally spaced elongated fluid conducting tubes providing elongated fluid pass structures and operatively connected thereto in heat transfer relationship and for spacing said elongated fluid conducting tubes, each of said fin structures including a plurality of spaced and transversely extending fin strip elements operatively connected to the respective elongated fluid conducting tubes between which they are associated in heat exchange relationship, each of said fin strip elements including a plurality of relatively narrow and substantially planar fins having their ends operatively connected to the opposite sides of the elongated fluid pass structure formed by the respective elongated fluid conducting tubes operatively associated therewith in heat transfer relationship, the respective relatively narrow and substantially planar fins extending transversely of the axis of fluid flow through each respective elongated fluid pass structure, said relatively narrow and substantially planar fins of each fin strip element being arranged in a plurality of spaced groups, each of said spaced groups extending across the respective elongated fluid pass structure transversely to said axis of flow therethrough, each of said relatively narrow and substantially planar fins extending at an angle with respect to the direction of flow, all of the relatively narrow and substantially planar fins of each spaced group extending in the same general direction, the angle of relatively narrow and substantially planar fins of each spaced group being reversed with respect to the angle of the relatively narrow and substantially planar fins of the next adjacent spaced group, and a deflecting fin member positioned between said spaced groups of reversely directed and relatively narrow and substantially planar fins, each deflecting fin member including portions respectively extending in the same angular'di-rection as the relatively narrow and substantially planar fins of the spaced groups to provide undulating fluid flow paths through said elongated fluid pass structure.

4. A fin structure for a heat exchange structure comprising a plurality of laterally spaced elongated fluid conducting tubes and between which said fin structure is operatively associated in heat transfer relationship to provide an elongated fluid pass structure therebetween, said fin structure including a plurality of spaced and transversely extending fin strip elements for operatively connecting to the respective elongated fluid conducting tubes of the heat exchange structure, each of said fin strip elements including a plurality of relatively narrow and substantially planar fins and the ends of said planar fin for operatively connecting to the opposite sides of an elongated fluid pass structure, the respective relatively narrow and substantially planar fins extending transversely of the axis of fluid flow of the respective fluid pass structure therefor, said relatively narrow and substantially planar fins of each strip element being arranged in a plurality of spaced groups, each of said spaced groups extending across the fin structure transversely to said axis of flow through the fluid pass structure, each of said relatively narrow and substantially planar fins extending at an angle with respect to the direction of flow, all of the relatively narrow and substantially planar fins of each spaced group extending in the same general direction, the angle of the relatively narrow and substantially planar fins of each spaced group extending in the same general direction, the angle of the relatively narrow and substantially planar fins of each spaced group being reversed with respect to the angle of the relatively narrow and substantially planar fins of the next adjacent spaced group, and a deflecting fin member positioned between said spaced groups of reversely directed and relatively narrow and substantially planar fins, each deflecting fin member including portions respectively extending in the same angular direction as the relatively narrow and substantially planar fins of the spaced groups to provide undulating fluid flow paths through said elongated fluid pass structure.

5. A fin structure for a heat exchange structure according to claim 4, wherein each of said fin strip elements is channel-shaped and including parallel flanges extending along opposite edges thereof, each of said flanges having at its free edge a marginal portion oflset outwardly a distance substantially equal to the thickness of the strip element so that the channel-shaped fin strip elements are nested together for aflixing to said spaced, elongated fluid conducting tubes in heat transfer relationship and providing said plurality of spaced and transversely'extending fin strip elements, and the base of each of said channel-shaped fin strip element including said spaced groups of said plurality of relatively narrow and substantially planar fins, and said deflecting fin member positioned between said spaced groups of reversely directed and relatively narrow and substantially planar fins to provide said undulating fluid flow paths through said elongated fluid pass structure.

6. A fin structure for a heat exchange structure according to claim 4, wherein said fin structure is serpentine in shape and includes a plurality of said spaced and transversely extending fin strip elements integrally connected adjacent corresponding edges providing corrugations for aflixing to said spaced, elongated fiuid conducting tubes in heat transfer relationship and providing said plurality of spaced and transversely extendingfin strip elements, and each of said fin strip elements between the corrugations thereof including said spaced groups of said plurality of relatively narrow and substantially planar fins, and said deflecting fin member positioned between said spaced groups of reversely directed and relatively narrow and substantially planar fins to provide said undulating fluid flow paths through said elongated fluid path structure.

References Cited in the file of this patent UNITED STATES PATENTS 1,336,136 Harrison Apr. 6, 1920 1,679,517 Fedders Aug. 7, 1928 2,063,757 Saunders Dec. 8, 1936 2,696,976 Boestad et al. Dec. 14, 1954 2,703,700 Simpelaar Mar. 8, 1955 

